Tapas has been my best experience hands down. Everyone is so nice and accepting. I went back to Wattpad after deleting it but only because it was my first server.
Some tips are tag, tag, tag like your life depends on it, and social media.
Tumblr:
Helped me a lot with promoting. Trick about tumblr is that the first five tags are the ones the system pays mind to. So tag your work with the best top five you can think of. Ex: Tapas, novel, [insert genere], etc.
Forums:
Coming on here and promoting in forums (that allow and ask you to promote) also works out. It's how I got subscribers really fast when I started here. I deleted my account, which was a mistake, but I'm doing the same stuff and climbing back up again with subscribers. So forums really help.
Twitter:
Look for the most popular writing tag and use that one, talk about writing. Being funny attracts people to check out your stuff. For tags, I use the recently created #Tapasnovel, made by a Tapas novel writer @rewashington, and #WritingCommunity. WritingCommunity isn't for promoting, but connecting with other writers so be careful not to spam.
(I didn't mention @rewashington to make this point, but it made me realize that mentioning them is thanks to both tags and this forum. See my point? Their name is getting around and hopefully, someone gets curious and clicks on their profile and novel.)
Lastly:
Post weekly
Connect with your readers
Talk to other writers
Enjoy the ride
If you love your story others will too. You show your love by talking about it, and sharing it.
Hope this helps 